Die casting machines generally employ two cooperating die halves. When the dies are in a closed position, molten casting material is poured into the machine to fill the interior cavity between the die halves. Of course, the die halves are rigidly locked together during this step of the casting process.
Once casting is complete and the casting material has hardened, the workpiece needs to be removed. This requires separating the die halves, as well as separating the workpiece from the die halves.
A number of means for moving the die halves with respect to one another and for locking them in a closed position are described. A mechanical closing and opening means is described, for example, in U.S. Pat. No. 4,815,518. With this approach, two exterior casting plates, each capable of housing one of the die halves, are mounted on a slidable frame that is manually positioned using a rack and pinion assembly. A second, manually operated rack and pinion assembly is used to position a core or plug on each side of the casting plates to make contact with each of the die halves. When the casting material has hardened and the workpiece is to be removed, one or both of the plugs on each side of the die are moved slightly with respect to the die to release one of the plugs from the die. Thereafter the die halves can be moved by actuating the slidable frames holding the die halves. This exposes one half (in some cases, all) of the workpiece.
This mechanical approach to die closing and opening for die casting machines is an advantage because the die moving and workpiece separating actions are accomplished by separate mechanisms. Nonetheless, the manually operated system is useful for casting only limited quantities of articles and requires skilled operators.